This invention relates to a method of validating a procedure in a network protocol. In particular, the invention relates to a network protocol such as the Intelligent Network Application Protocol (INAP) required for support of Capability Set 1 (CS1) defined in the European Telecommunication Standard ETS 300 374.
In a protocol such as INAP CS1, there exist a number of valid procedures, or sequences of operations, which can be carried out to perform specific tasks. However, since the number of possible procedures is large, the valid procedures are not defined directly, but rather are defined by means of a set of rules. Any procedure, or sequence of operations, which does not violate these rules, is then considered a valid procedure.
In the prior art, the rules can be described by defining a finite state machine (FSM) in respect of each entity, and each interface, an interface being a boundary between two entities. The FSM then acts as a model for the behaviour of a process. An FSM consists of states, which can be connected to each other. A process can only be one state at any one time, but can move from one state to a connected state as a result of an event. On the transistor from one state to another, actions can be performed. Such a system is described in KAKUDA et al, xe2x80x9cA Dynamic Resolution Method for Feature Interactions and its Evolutionxe2x80x9d, Feature Interaction In Telecommunications Systems III, pages presented at the third Feature Interactions Workshop (FIW""9, KYOTO, JP, Oct. 11-13, 1995).
When using an FSM to validate a procedure in a network protocol, the events which control the FSM are then operations defined in the protocol, or other events coming from other processes, such as the call process. The rules, which define the valid procedures in a network protocol such as INAP CS1, are the Single Association Control Function (SACF) and the Multiple Association Control Function (MACF) rules. The SACF rules apply where there is a single association, and the MACF rules apply where there are several related associations, an association being a signalling channel, using a specific interface, which allows communication between two entities.
Unfortunately, describing all of the SACF rules and MACF rules formally with a single FSM requires an excessively complex FSM. The result is that many procedures, including all MACF procedures, are still defined in natural language. There are no mechanisms to validate rules for this type of procedure, namely procedures which cannot be specific in terms of a single FSM per association.
The present invention is concerned with a method of validating a procedure by allowing the rules to be specific by multiple FSMs. Specifically, several processes, each running a specific FSM, are allowed to be involved in the validation of a single event.
The validation of an event takes place in two phases. Firstly, the relevant processes are selected, by assessing whether they meet specific criteria. In the second processing phase, all of the selected processes process the event.
This has the advantage that all of the involved processes are in a stable state, before an event is processed by any of them.